M.Simons The World's Vintage Sailplanes 1908-45
THE PWS 101
Waclaw Czerwinski moved to the National Aircraft Factory of Poland as chief designer in 1936. Whilst working on two new fighter aircraft, the PWS management decided to make use of his experience as a successful sailplane designer,
planning to enter glider manufacturing as a sideline. Czerwinski produced the PWS 101 to represent Poland at the 1937 International competition at the Wasserkuppe.
The wing had a strong, very stiff box spar with a plywood covered leading edge. Czerwinski stressed the structure for a maximum airspeed of 290 km/h. Large ailerons of broad chord were used, divided into two sections. They were slotted, mass balanced against flutter, and differentially geared. The airbrakes were of quite unusual design. A slot was built through the wing just aft of the mainspar at about one third of the chord from the leading edge. In normal flight, plates closed the slot, but when the airbrakes were deployed the lower hinged plate, opening with its lip upstream, scooped air into the slot, and the upper plate, opening with its hinge along the upstream edge, hurried the air from below out on to the upper wing surface. The effect was not only a great increase in drag but a marked spoiling of the lift. Another disadvantage was that the stalling speed increased.
As was fashionable, the wing was given ‘gull’ dihedral and mounted on the fuselage in the mid position with simple but quite efficient root fairings.
The fuselage was of oval cross-section, a plywood semi-monocoque structure with a large cockpit and fully enclosed canopy. A back-type parachute box was built in, and there were additional windows behind the pilot's head so that he could obtain a good view into turns. Full blind-flying instruments were standard. The landing skid was the usual length of laminated ash with a long inflated tube fixed between the keel and the skid. Provision was made for 50 kg. of water ballast for flying on days with strong thermals.
The elevator trim tabs acted as anti-balance tabs when the stick was moved, increasing the ‘feel’ or handling loads for the pilot. Since the elevator was already of large chord, this must have made the stick very heavy. This feature was considered an advantage for cloud flying since, once trimmed, the PWS 101 would fly very stably without much attention to airspeed control by the pilot.
Two PWS 101 sailplanes were ready for the Wasserkuppe meeting. On the first day of the competition Mynarski, in a PWS 101, was right up with the great Heini Dittmar and Hanna Reitsch at the top of the list with a flight of 351 km. All three landed at Hamburg. Mynarski’s flight set a new Polish record for distance.
Several more of the type were completed. In 1938, on 18th May, Tadeusz Gora made a flight of 577.8 km from Bezmiechowa to Sloneczniki Male. This was not only a new Polish record distance, but with one exception was the longest flight ever made by a sailplane. It was not a world record because Victor Rastorguyev in the USSR had achieved 652 km in the previous year. At the end of 1938 Gora was awarded the Lilienthal Medal. Soon afterwards the German and Russian invasion of Poland brought all gliding there to a halt and all but a few sailplanes were destroyed.
PWS 101: Span, 18.99 m. Wing area, 18.9 sqm. Aspect ratio, 19. Structure weights: Wing, 120 kg; fuselage and tail, 95.3 kg; equipment, 5.4 kg; ballast, 49.9 kg; total, 270.6 kg. Flying weight (maximum) 354.5 kg (normal without ballast, 304.6 kg). Wing loading, maximum 18.76 kg/sqm. (without ballast I6.4kg/sqm). Aerofoils, special. Best glide ratio, 1 : 27.
A PWS 101 at the Wasserkuppe in 1937. This fine photograph was subsequently used by the German authorities for publicity purposes with the Polish national registration number SP 1006 obliterated from the rear fuselage for political reasons.
Sister ship to SP 1006, the PWS 101 SP 1005 seen flying over the Wasserkuppe. Polish sailplanes at the 1937 Internationals were painted in the national colors of red and white.
One of the Spyr 3s flown by Bauer at the International Competitions in 1937. The contest number 9 on a red and white striped diamond, and the words Zwieback Singer, appeared on the fuselage. Other sailplanes visible are, on the left, the Czechoslovakian Tulak 37 (registered OK-CECHY) and on the right, one of the Polish PWS 101s (SP-1005) with a Condor beyond it.